04 Fakultät Energie-, Verfahrens- und Biotechnik
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Item Open Access Biological effects of shock waves(1990) Brümmer, Franz; Bräuner, Thomas; Hülser, Dieter F.Extracorporeal shock wave lithotripsy has become established worldwide as the method of choice for the treatment of nephrolithiasis and ureterolithiasis over the last 10 years. Although initial studies showed no damaging effects of the shock waves on organs and tissues, numerous recent reports have presented evidence for severe acute effects and chronic complications after shock wave treatment. The pathophysiological effects on kidneys and the histopathological effects on organs or tissues in man and animal, and also the effects on cells in culture and tumors are sumarized. Suspended and immobilized cell cultures were used to characterize and quantify the efficacy of shock wave. Extended applications of shock waves and possible modifications to shock wave generators are discussed.Item Open Access Introduction - Symposium on Intercellular Communication Stuttgart, 1982(1982) Hülser, Dieter F.Intercellular communication is a postulate of complex multicellular organisation. Signal transfer between cells is possible in different ways: 1.) Long distances of up to 1 m may be bridged by molecules which are produced in distinct cells and are released into the extracellular fluid where they are distributed and interact with receptors on the surface of their target cells (e.g., humoral interaction). 2.) Transmitter substances which have a limited life span or which can be inactivated by inhibitor molecules spread signals only over shorter distances (e.g., synaptic cleft, -200nm). 3.) Information can also be exchanged by direct membrane contact when two molecules interact with each other directly or via linker molecules (e.g., immune system). 4.) Intercellular communication is also possible by channels between adjacent cells, which permit the exchange of ions and molecules and the spread of electric currents; many of those pores are arranged in the membranes of the contacting cells as a quasicristalline structure forming the gap junction. A national symposium on "Intercellular Communication" in Stuttgart on 16 and 17 September 1982 serving the aim of increased "interlaboratory communication" covered most of the above aspects.Item Open Access Membrane potential oscillations in homokaryons : an endogenous signal for detecting intercellular communication(1982) Hülser, Dieter F.; Lauterwasser, UrsulaFusion of cells by polyethylene glycol results in homokaryons with lower membrane input resistances than their parental cells, but otherwise unchanged membrane properties. With these large cells, long lasting intracellular recordings can be realized which are impossible with single parental cells. Homokaryons often display hyperpolarizing (up to 50 mV) oscillations of their membrane potentials. In electrically non-coupled cell lines (HeLa, L, Cl-1D) the frequencies of these endogenous signals are 3 oscillations per min. Trypsinized homokaryons of electrically coupled cell lines (BICR/M1R-K, 3T3, BT5C2) have frequencies of 0.3 oscillations per min. By recording the membrane potential oscillations of two contacting homokaryons, the formation of low resistance junctions was followed - without applying exogenous signals - by a superposition of the individual oscillations. Our electronmicroscopical investigations revealed that the intercellular coupling through the membranes of homokaryons can be attributed to gap junctions.Item Open Access Tumor cell invasion and gap junctional communication. 1, Normal and malignant cells confronted in monolayer cultures(1990) Bräuner, Thomas; Schmid, Andreas; Hülser, Dieter F.Mammary tumor cells of the rat (BICR/MIR k) and mouse (EMT6/Ro) as well as rat glioma cells (C6) are electrically coupled and show intercellular dye spreading. Monolayer cultures of synchronously beating chicken heart cells were also electrically coupled, dye spreading. however, was significantly restricted to only one or two adjacent cells. In all coupled cells, gap junctions were found in both freeze-fracture replicas and ultrathin sections. Heterologous gap junctional coupling between these tumor cells and heart cells was regularly established. The human cervix carcinoma line Hela and the mouse L sarcoma line were elcctrically not coupled and did not reveal gap junctions, consequently they showed no coupling to heart cells.Item Open Access Pattern analysis of gap junction plaques with open and closed pores(1985) Müller, A.; Blanz, Wolf-Ekkehard; Laub, Gerhard; Hülser, Dieter F.The structure of freeze-fractured gap junctions was studied by electron microscopy and subsequent pattern analysis using a computer controlled image processing system. Rat mammary tumor cells (BICR/WIR-k) which are permanently coupled via gap junctions when cultered as monolayers were used under different fixed and unfixed conditions. Active (coupling competent) gap junctions seem to be characterized by loosely packed connexons, whereas non-active (permanently closed) gap junctions may consist of tightly packed particles.Item Open Access TNF receptors TR60 and TR80 can mediate apoptosis via induction of distinct signal pathways(1994) Grell, Matthias; Zimmermann, Gudrun; Hülser, Dieter F.; Pfitzenmaier, Klaus; Scheurich, PeterTNF membrane receptors are usually co-expressed in many tissues but their relative contribution to cellular TNF responses is for most situations unknown. In a TNF cytotoxicity model of KYM-1, a human rhabdomyosarcoma cell line, we recently demonstrated that each of the two TNFRs is on its own capable of inducing cell death. Here we show that both receptors are able to induce apoptosis, as revealed from a similar onset of DNA fragmentation and typical morphologic criteria. To obtain additional information about the signaling pathways involved in TR60- and TR80-induced programmed cell death, we have used a series of selective inhibitors of intracellular signaling molecules. The overall pattern emerging from these experiments provides strong evidence for distinct signal pathway usage of TR60 and TR80, indicating protein kinase(s)-mediated control of TR60 signaling and a tight linkage of TR80 to arachidonate metabolism. The subsequent establishment of KYM-1·derived cell lines that display TNFR selective resistance further supports a segregation of TR60 and TR80 signaling pathways for induction of apoptotic cell death. Moreover, these results demonstrate an independent control of the distinct signaling cascades used by TR60 and TR80. This allows a highly flexible regulation of a cellular TNF response in those cases in which both receptors contribute to overall TNF responsiveness.Item Open Access A million cells in search for contact : multicell spheroids not only for cancer research(1987) Hülser, Dieter F.; Brümmer, Franz; Bräuner, ThomasThree-dimensional, spherical aggregates of cells - so-called multicell spheroids - have many practical applications. In cancer research, for example, they contribute to a drastic reduction in the number of experiments with animals. The authors of the following article were awarded a special DM 10,000 prize under the Felix-Wankel-Tierschutz-Forschungspreis in November 1986 for their work on intercellular communication in multicell spheroids.Item Open Access Sensivity of normal and malignant cells to shock waves(1992) Brümmer, Franz; Suhr, Dierk; Hülser, Dieter F.We examined the cytotoxic effect of shock waves for primary (embryonic chick kidney and thigh muscle) and permanently growing normal and malignant cells (human, rat, and mouse) in suspension. To avoid the influence of different media, the cells were suspended in phosphate buffered, saline and shock wave treated. In all cases the acute cytotoxic effect (measured by flow cytometry) was a function of the applied shock waves. The investigated cells differed in their LD 50 values which, however, do not reveal a general difference in sensitivity to shock waves for normal and malignant cells.Item Open Access Timing the early events during sea urchin fertilization(1983) Schatten, Gerald; Hülser, Dieter F.To determine precisely the timing, duration, and sequences of the earliest events during sea urchin (Lytechinus variegatus) fertilization, the bioelectric recordings of microelectrode-impaled eggs were electronically superimposed, by video mixing, over the microscopic differential interference contrast image of the same egg at insemination. Videotape analysis, utilizing a slow-motion analyzer, demonstrates that the successful sperm triggers the bioelectric membrane potential reversal within 3.36 ± 3.02 sec (0.72-9.76 sec range; Σ = 23 eggs) of sperm-egg attachment. This sperm, actively gyrating about its attachment site, is indistinguishable from the other, unsuccessful sperm until 12.66 ± 2.72 sec (6.72-16.60 sec range; Σ = 15) later when the sperm tail ceases its beating and sperm incorporation ensues. The cortical granules begin to discharge, and the fertilization coat starts to elevate at the fusion site at 20.79 ± 3.18 sec (13.62-26.08 sec range; Σ = 12) after the onset of the fertilization potential, i.e., an average of about 8 sec after the cessation of sperm-tail motility during incorporation. In most cases, the bioelectric responses starts within 7 sec of sperm adhesions; if the data are analyzed excluding the few slow cases, the fertilization potential is found to start 1.93 sec (±1.28 sec) after sperm attachment. These results indicate that the first successful sperm triggers the fast block to polyspermy within 3.4 sec, perhaps as quickly as 1.9 sec, of sperm-egg adhesion, about 13 sec before the first morphological indication of fertilization, and about 21 sec before the characteristic elevation of the fertilization coat responsible for the late block to polyspermy.Item Open Access Retinoic acid modulates gap junctional permeability: a comparative study of dye spreading and ionic coupling in cultured cells(1991) Brümmer, Franz; Zempel, Günther; Bühle, Peter; Stein, Johannes-Christoph; Hülser, Dieter F.All-trans retinoic acid (RA), which was recently identified as a morphogen, affects gap junctional permeability in a dose- and time-dependent manner. In five different established mammalian cell lines (FL, BRL, BICR/M1Rk, HEL37, BT5C1) 100 μmol/liter RA reduced Lucifer yellow spreading within 30 min to 20-50% of the control. Ionic coupling, however, remained almost unaffected under the same conditions. Freezefractured membranes of untreated and RA-treated cells were similar with regard to frequency and sizes of gap junction plaques. With concentrations of less than 10 μmol/liter RA the dye spreading increased significantly in the human amniotic cell line FL, pointing to a possible modulatory effect of RA on junctional communication.